CODEWITHSUNDEEP
javascriptbrowser
Allerson
Allerson

Reputation: 109

How to force refresh client js from server side?

Here is the case:

I get a js to monitor web ads.Because of the browser cache,when i update js on server side,js on client side will not be refreshed immediately.How could i force refresh client js as soon as i update js on server side?

p.s. Add version number strategy is not useful in my case.

Upvotes: 4

Views: 14063

Answers (3)

MD Sayem Ahmed
MD Sayem Ahmed

Reputation: 29166

Simple strategy - add a version number as a query string to your js files, and change the number. This will cause the browsers to fetch your js files again - 

<script src="mysource.js?version=123"></script>

Whenever you change your script on the server, change this version number in the html too. Or better yet, apply a random number as the version value every time you request this script.

Upvotes: 9

Wyzard
Wyzard

Reputation: 34563

You can use HTTP's cache-control mechanisms to control the browser's caching.

When serving a copy of your JS file, include an ETag and/or Last-Modified header in the response. Also include a "Cache-Control: must-revalidate" header. This tells the browser that it must check back with the server every time, and it can send an If-None-Match and/or If-Modified-Since header in future requests to ask the server to send the file only if it's changed.

If you'd like to avoid the load of browsers checking with the server every time, and it's OK for the changes to not take effect immediately, you can also include a Date header with the current time and an Expires header set to some point in the future — maybe 12 or 24 hours. That allows the browser to use its cached copy for the specified amount of time before it has to check back with your server again.

HTTP's cache-control features are pretty robust, but there are plenty of nuances, such as controls for intermediate caches (e.g. other systems between your server and the user's browser). You'll want to read about caching in HTTP overall, not just the specific header fields that I've mentioned.

Upvotes: 3

enenen
enenen

Reputation: 1967

You can do this by changing the name of the file. Add some version number (could be like parameter, i.e. filename.js?v=time(); for PHP for example) or just append some random numbers at the end of the filename.

Actually I'm not sure whether you can force the client to refresh this type of files. But when changing the file name you will force the browser to get the newest version.

Upvotes: 2

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